The core body temperature of a healthy human being usually remains at about 98.6 degrees F. When the core body temperature varies significantly either above or below this level, a human being can experience great suffering and damage to his or her health, possibly resulting in death. If the core body temperature drops significantly below levels compatible with health and survival, the condition is referred to as hypothermia. If the core body temperature rises significantly above levels compatible with health and survival, the condition is referred to as hyperthermia.
In its most basic form, the first aid treatment for the condition of hypothermia involves removing the affected person from the low temperature environment, and wrapping the affected person in a blanket. Similarly, basic first aid treatment for the condition of hyperthermia involves removing the affected person from the high temperature environment, and stripping the clothing off of the affected person.
Recognizing that these basic forms of first aid treatment are too crude to prevent death in serious life-threatening cases, various methods have been devised for the treatment of hypo- and hyperthermia through the use of external heating or cooling sources to raise or lower the core body temperature of the affected person. These methods are categorized generally as either direct or indirect methods of treatment.
In the direct method of treatment, the warming or cooling sources are applied directly to the core areas of the human body, such as the lungs, esophagus, and circulatory system, in an attempt to allow caloric transfer to be accomplished by conduction or convection with the body core. This method of treatment can be reasonably effective, but because of the invasive nature of the treatment procedure, this method is normally administered within a hospital setting.
Frequently, however, the person suffering from the hypo- or hyperthermic condition is located in a remote outdoor location, such as in a forest, at a beach, or on a river or lake. The person may have traveled to the remote location to enjoy some outdoor recreational activity, such as boating, swimming, mountain climbing, hiking, or jogging, or may have traveled to the remote location because their livelihood involves work in the outdoors, for example, as a logger or drill rig worker. By the time such a person suffering from either hypo- or hyperthermia arrives at the hospital, it is often too late to ensure his or her survival using the direct method of treatment described above.
In the indirect method of treatment, warming or cooling sources or fluids are applied to surface areas of the human body in an attempt to allow caloric transfer to be accomplished by conduction through the surface of the skin to the body core. Thus, theoretically, this method of treatment has the advantage over the direct method in that it is non-invasive, and therefore may more easily be performed outside the hospital setting.
However, while theoretically not requiring a hospital environment, the various devices designed to use the indirect method of treatment have often proved to be so bulky and awkward that they have not proven suitable for widespread first aid use outside of the hospital. Moreover, even when used in the hospital, these devices may be relatively ineffective. When used outside of the hospital, the effectiveness of such devices may decrease to the point that the treatment is completely ineffective.
For example, devices have been devised which circulate a warming or cooling fluid over the surface of the body in attempt to raise or lower the body core temperature. Examples of such devices can be seen in U.S. Pat. Nos. 4,572,188; 5,106,373; 5,184,612; 5,300,101; 5,300,102; 5,324,320; 5,336,250; 5,350,417; 5,383,918 and 5,405,371. These devices are bulky, require a great deal of space to set up, and are not designed to be easily used in those remote locations, such as beaches, forests, and mountains, from which a significant percentage of hypo- and hyperthermia cases originate.
Alternatively, devices have been suggested where a thermal energy exchanging mechanism, such as a plurality of tubes conducting a cooling or warming fluid, a plurality of electrical heating elements producing thermal energy electrically, or a plurality of heat sources using energy released as the product of a chemical reaction, is contained within a close fitting garment which is then pulled over or strapped tightly to a surface of a body. Examples of such devices can be seen in U.S. Pat. Nos. 546,436; 3,507,321; 4,685,462; 5,018,521; 5,269,369; 5,411,542 and 5,470,353. However, because these devices fit snugly to the surface of the body, these devices may be difficult to fit onto the affected person. Once in place, these devices may not be easily removable, and thus may impede other medical treatments necessary for the survival of the affected person.
While not directed to the treatment of hypo- or hyperthermia, warming or cooling devices have also been designed which support a thermal energy exchanging mechanism in a close-fitting relationship with a surface of a body for heating or cooling by providing a shaped or contoured padding material between an article of clothing worn by the person and the thermal energy exchanging mechanism. An example of such a device can be seen in U.S. Pat. No. 5,123,407.
However, there is no discussion in U.S. Pat. No. 5,123,407 of using such a device to treat hypo- or hyperthermia. Furthermore, in operation, the padding material is designed to maintain a predetermined contour such that the padding material does not adjust the energy exchanging mechanism to achieve the necessary continuity of contact between the energy exchanging mechanism and the surface of the body to allow for efficient treatment of hypo- or hyperthermia. Rather, the padding material generally attempts to force the underlying body surface to conform to the contours of the energy exchanging mechanism and the padding material.
Moreover, all three groups of devices fail to target the critical thermal energy transfer areas of the body. It is well documented that the most critical areas for thermal energy transfer to the body core through the skin surface are the head, neck, axilla, and groin. None of the present devices, as described above, effectively addresses the selective application of a warming or cooling source to these most critical areas of the body for the treatment of hypo- or hyperthermia.